Is AT&T blocking use if invisible ink in iPhones with OS 10?

My friend's iPhone from AT&T with OS10 does not receive invisible ink messages. It just receive a line of text saying it was sent in invisible ink. The same thing is true of all the other text features such as loud or gentle. Is AT&T blocking these? He can send them to me but they do not appear correctly on his phone. I checked with other AT&T users and found the same thing. My iPhone is with another carrier and works well with my wife's phone from the same carrier.